Rotary drill bit



June 10, 1958 B. L AUSTIN 2,833,285

ROTARY DRILL BIT Filed April 19, 1956 2 Sheets-Sheet;

BEAM/7mm L. flusrnv,

INVENTOR.

June 10, 1958' B. AUSTIN 2,838,286

ROTARY DRILL BIT Filed April 19, 1956 Y I 2 Sheets-Sheet 2 BENJAM/A/ L.Hus

' INVENTU the hole bottom 1 cutting face selves,

nited States 2,838,286 RQTARY DRILL BIT Benjamin Austin, Ogden, Utah,assignor to Christensen Diamond Products Company, Salt Lake City, Utah,a corporation of Utah Application April 19, 1956, Serial No. 579,299

8 (Claims. (Cl. 255-72) embedded therein, and to cool such faces anddiamonds.

Heretofore, the aforementioned intended purposes have not beenaccomplished efficiently. The cutting faces and the diamonds embeddedtherein have not beencl'ea'ned properly, reducing the penetration rateofthe diamonds in the formation. Reduction of penetration rate isattributable to some extent to the operation of the diamonds uponpreviously made cuttings remaining between the diamonds and undisturbedformation. It is also caused by the packing of the cuttings between thediamonds, preventing the latter from contacting the .bottom of the hole.Instead, thecuttings packed on the bit skid or slide along the holebottom, generating a large amount of heat which may be sufficient tomelt or burn a portion of the matrix material in which the diamonds areheld, with consequent dropping out or loss of some diamonds from thebit. Substantial generation of heat will occur, since the inability ofthe circulation fluid to cleanthe drill bit also militates against itscooling the bit, for the reason 'that the packed. cuttings prevent thefluid from fiowing'across the bit faces andthe diamonds themselves.

Attempts have been made to clean and cool the bit by providing groovesor watercourses in 'thecutting faces of the bit, through which.circulation fluidwill flow.

The cutting facesgand, diamonds adjacent: the watercourses there .willbemore. diamonds around the outer portion of H thanaround the inner.portion f such, cutting face. The watercourses, however,

-have ;l1 eretofore been much furthergap'artat the outer portionof thecutting facefthan at"itslinner portion, re-

- sulting in the la'cl'c of .pr'oper'cleaiiing oflthe. cutting facesand, diamonds at. the outer'portion ofth bit, except, possibly,immediately adjacent the watercourses them- Accordingly, itjis an'objectof the' present invention to .impr'ovedrotaify' drill bit havingadiamond provide an studded drilling face, which can be maintained in aclean and. cool'fs'tate by'th'e circulating 'fiui'd during the drillingof aihole'infthe formation, thereby enhancing the penetra'ti'oh rate ofthe bit and increasing its useful life.

Another objectof the inventionis to-provide-a rotary diamond drill bithaving watercourses in its; cuttingface arranged in such manner as .tocause the circulating fluid .to flow from one watercourse to anotheracross the diamond studded cutting face, cleaning and cooling allportions of the latter., The outer portionsof the cutting face arecleaned and cooled as effectively as its inner portions.

A further object of the invention is to provide. a rotary diamond drillvbit embodying watercourses that are-spaced apart by substantiallyuniform and-relatively short'distances across the entire bottom'holecontactingface or faces of the bit, to insure circulation of thedrilling fluid across all portions of such contacting face or faces andtheir-maintenancein a clean 8.1'1d1C00l condition.

An additional object-of the; invention .is to provide a rotary diamonddrill bit having watercourses-in its cutting face or faces arranged in'such manner as to result in a substantially uniform concentrationofdiamonds on its cutting face or faces between the watercourses perunit of projected area, and an'eflective cleaning and cooling of allareas of such cutting face or faces. The

outer'portions'of the cutting face or faces are cleaned as effectively'as the inner portions.

Still a further object of the invention is to provide ta rotary diamonddrill bitembodying watercourses spaced from one another by relativelyshort distances to"pro viderelatively narrow spans or lands betweenwatercourses in which the diamonds are held, the watercourses being soarranged that circulating fluidnot only travels through the watercourses, but also flows between watercourses and across the lands to cleanandtcool them.

parentfrorn a consideration-of a form in which it may beembodied.This-form is shown in the drawings-accompanying and forming part of thepresent specification; It will now be described in detail, for'thepurpose of illustrating the general principles of the invention; but it:is to be understood that such detaile'ddescription is not to be takenin a limiting sense, since the scope of the inventionis best defined bythe appended claims. Referring to the drawings: 7

' Figure 1 is a combined side elevational and longitudinal section of arotary core drilling bit embodying the invention; 7 p v 'Fig. 2 is across-section taken along the line 2-2 on Fig. l; p

Fig. 3 is .afragmentary bottom plan view of the .bit disclosed in Fig.l;

5 ig. 4.is .an enlarged view similar to Fig. 3;

Fig. 15 is a section taken alongtheline 5-5 on Fig. 3.

The invention is illustrated .in the drawings as being applied to acorebit, which may form the, lower portion of an apparatus for taking a coresmple, the core passingupwardlyinto a core barrel (not shown) in aknownmanner. it .is to be understood, however, that in its broader. aspects,the invention is notlimited to core bits, but is directed to rotarydrill bits generally.

' As, disclosed in the drawings, the apparatus includes a tubular, mainbit body or shank lllhaving an upper threaded box 11 threadedly secured,onto the lower threaded-pin 12 of a tubular drill collar or drill pipe13 forming the lower end ofa drill string extending to the hasamatrix 17of-relativelyhard material, of any suitable type, secured to its outer,bottom, and inner surfaces, in which diamonds 18 of the proper size aresecured in a known manner. These. diamonds may project from the surfaceof the matrix 17 to the extent desired, or some of them may be flushwith the surface. They are arranged in a desirable pattern on theexposed faces 14, 15, 16 of the matrix, to operate upon the bottom andsides of the hole being drilled.

Circulating fluid, such as drilling mud, is pumped down the drill string13 during the rotation of the apparatus, this drilling fluid passingthrough relatively shallow longitudinal grooves or recesses 19 in theinner wall of the bit body and around the core barrel (not shown), thedrilling fluid discharging through the throat of the bit and onto thebottom of the hole. The drilling fluid will also flow outwardly alongthe bottom of the hole, to clean the hole of cuttings and carry themaround the outside of the bit and the drill string to the top of thehole, all generally in a known manner.

As specifically disclosed, the drill bit is provided with a convexbottom portion 14 merging into an inner surface 15 and also an outersurface 16. Since the bit specifically illustrated is a core bit, theinner surface 15 is substantially cylindrical, which is also true of theouter surface 16 which constitutes the reaming portion of the bit. Toenable the bit to drill hard formations, the matrix 17 has the diamonds18 embedded in the inner, lower and outer faces 15, 14, 16, thesediamonds being arranged in any desired pattern.

For the purpose of cleaning and cooling the cutting surfaces of the bit,a plurality of grooves 21 is formed in such faces in a particularmanner, providing watercourses through which the circulating fluid canflow readily from the interior of the bit to the bottom of the hole, andthence outwardly along the bottom of the hole, from where the fluid willflow in an upward direction past the reaming face 16. The grooves 21 arerelatively shallow, and are substantially equally spaced from each otheraround the cutting faces of the bit to provide spans or lands 22 betweenthe grooves in which the diamonds 18 are embedded. The grooves 21 extendalong the inner face 15, around the convex lower face 14, and upwardlyalong the outer reaming face 16 of the bit. The grooves are separatedfrom one another by relatively short distances to provide relativelyshort or narrow lands 22 therebetween in which the diamonds are embeddedand from which they may project. As shown, the groove portions 21a aresubstantially parallel to the axis of the bit along the innercylindrical face 15 of the matrix, the upper ends of these watercourseportions 21a opening into the bore 23 of the bit body or shank, toreceive drilling fluid therefrom. The groove portions 21b are arrangedin spiral fashion along the convex lower face 14 of the bit, the innerends of these spiral groove portions merging into the lower ends of thegroove portions 210 and their outer ends into inclined groove portions210 generally parallel to one another and arranged along the gauge orreaming face 16 of the bit. Each groove 21 is continuous beginning atthe upper end of the inner cylindrical face 15, where it communicateswith the main fluid passage 23 in the bit body, and then continuing downalong the inner cylindrical facelS and into the convex face 14, wherethe groove portion 21b is arranged in a spiral manner (at anincreasingly greater angle with respect to a radial line drawn from theaxis of the bit to the commencement of the spiral) outwardly toward thereaming face 16 of the bit, the groove then continuing as the inclinedportion 21c, as disclosed most clearly in Fig. l, to the upper end ofthe reaming face 16, where the groove portion has an outlet into thewell bore around the bit body 10. The inclined groove portion 21c makesa substantial angle to a plane radial of the bit axis.

The grooves 21 are separated from one another by the relatively shortlands or spans 22, and are also generally equidistant from one another,the lands each including an inner cylindrical portion 22a, merging intoa lower spiral portion 22b (which is also directed at an ever increasingangle to a radius. drawn through the beginning of the spiral portion),the spiral portion of the land running into an inclined land portion 220between the inclined watercourse portions 21c extending along theoutside diameter or reaming face 16 of the bit.

In the use of the apparatus, it is lowered in the well bore to thebottom of the hole, the proper drilling weight being then imposedthereon while the bit is rotating at the proper speed. During thedrilling action, circulating fluid, such as drilling mud, is pumped downthe string of drill pipe 13, and will pass through the main or centralpassage 23 in the bit body and the recesses 19 into the watercourses orwaterways 21. The fluid passes through the watercourse or grooveportions 21a in the interior of the bit and thence through the spiralportions 21b along the bottom contacting face 14 of the bit, thenpassing upwardly through the inclined watercourse portions 21c in theouter face 16 of the bit into the well bore annulus around the bit bodyor shank 10. The circulating fluid is pumped through the tool and thewatercourses 21 at a proper rate, and will flush the cuttings from thedrilling region in an outward direction and up around the bit and thedrill string 13 to the top of the well bore.

Not only does the fluid flow through the watercourses or grooves 21themselves, but it also flows transversely from the waterways across thediamond-studded lands 22 to other waterways in a substantial quantity,removing the cuttings between the diamonds 18 on the lands and coolingthe lands. The fluid effectively prevents cuttings from packing betweenthe diamonds 18, which would minimize the extent of penetration of thediamonds into the formation. The effective cleaning and cooling actionof the fluid passing across the lands 22 from one waterway to the nextwaterway is due to the fact that the fluid flowing downwardly throughthe throat 20 of the bit and its inner waterway portions 21a tends tofollow a straight line path and resists attempts to confine it forlateral outward flow along a curved path, such as through the spiralwaterway portions 21b. Some of the fluid, therefore, moves out of onewaterway 21, and flows across a land 22 to the next adjacent waterway onthe opposite side of the land. In flowing across the land, it cleans andcools the face of the land and the diamonds projecting therefrom.

The tendency for the fluid to flow along a straight line path, which, inthe present instance is generally radially of the bit in an outwarddirection is enhanced by the fact that a pressure differential existsbetween different points of adjacent curved or spiral watercourseportions 21b. Each watercourse or groove portion 21b may be consideredas a conduit through which fluid is flowing, since the formationsubstantially closes its open side. Inasmuch as the watercourse isrelatively shallow, and particularly since the circulating fluid isusually a comparatively heavy drilling mud, there will be a progressivepressure drop in each watercourse commencing from its inlet and runningto its outlet portion. As shown diagrammatically in Fig. 4, the pressurein a watercourse portion 21b at the point a will be greater than thepressure at the point b, which will be greater than at a point 0 furtheralong the watercourse. In other words, the pressure will progressivelydecrease along the length of each watercourse. Since the fluid tends toflow along a straight line path, or in a generally radial direcn'on, itwill tend to cross a land, travelling from different points in onewatercourse portion 21b to the next watercourse portion 21b, reachingthe next watercourse portion at greater distances from its inlet a thanits points of exit from the first-mentioned watercourse portion.

The following example is given of the foregoing statement, referencebeing had to Fig. 4. The pressure in a watercourse drops progressivelyalong its length, decreasing pmsre si e at he p in s .a, h corre- 5,sponding points in the next watercourse are designated a b 11 ,3 Sincethe drilling fluid tends to resist following a curving flow path, fluidin one watercourse at point tends to continue movement in a straightline path S across a land 22 to the next watercourse, entering thelatter at the point al This point d is at a much greater distance fromthe entrypoint a of the watercourse than is the point b from the entry aof its Watercourse. Accordingly, in view of the progressive pressuredrop along each watercourse, the pressure at point b will besubstantially higher than at point d producing a pres sure differential,which induces the fluid to leave one watercourse and flow across theland to the next watercourse. In so flowing across the land, it cleansit of detritus and cools it as well. The fluid from point b not onlyfollows the straight line path S, but also flows more directly acrossthe land, in view of the lesser pressures at other points of the nextwatercourse. Thus, the pressure at point 0 is less than at point 12,some fluid at the point b flowing along the path T to the point c It isevident that the pressure differentials between the watercourses willproduce a general transverse flow across the lands 22 from onewatercourse to the other, and such transverse flow coupled with flow offluid through the watercourses themselves, will thoroughly clean thebottom of the hole of the cuttings, completely flushing such cuttingsfrom each land and insuring its maintenance in a clean and a coolcondition.

It is to be noted that the distance between watercourse portions 215 isvery little greater at the outer region of the bit bottom than, at itsinner region. The lands 22b themselves are of substantially uniformwidth, possibl being only slightly wider at their outer regions than attheir. inner regions. The spiral arrangement of watercourses or grooves21b results in such substantial uniformity of widths oflands ZZband ofwatercourses 21!) across. the bottom face of the bit. It also results intheability to concentrate diamonds across thebottorn *face of the bitinsuch manner that'they are uniformly disposed per unit or square inchof projected area, the substantially uniform disposition andconcentration of diamonds being maintained from the inside diameterofthe bit to the outside diameter or reaming face 16 of the bit. Suchsubstantially uniform concentration of diamonds per unit of projectedarea equalizes the work which'is done by each diamond or stone ontheface of the bit, inasmuch as there are obviously more diamondsavailablefor cutting action at the, outer portion of the bottom cuttingface 14 than at the inner portion. The general uniformity of dispositionof the stones 18 on the faceof the bit perunit-of prQjecte'darea insures-a more uniform rate of wear of the diamond stones, and results in agreatly increased life of the drill bit.

It is evident that the spiral fluid course pattern, which produces thespiral lands 22 containing the diamonds,

provides a substantially uniform concentration of diamonds from theinside of the bit to its outside diameter without substantially Wideningthe lands adjacent the outside diameter of the bit, which would have thedrawbac; of the watercourses 21 being widely separated, di-

minishing the flushing action of the circulating fluid across the landsor spans 22 etween watercourses at the outer portion of the bit.

it is, accordingly, apparent that a rotary diamond drill bit has beenprovided, in which the bit is maintained in a clean and cool conditionby the circulating fluid, assurance being had that all cutting faces ofthe bit will be thoroughly flushed by the drilling fluid. The fluid doesnot only flow through the watercourses, but also transversely from onewatercourse across a land to an adjacent watercourse throughout thelength of the land, and, in so doing, insures the maintenance of allsurfaces of the lane face in a clean and cool. condition. Accordingly,there is no localized burning of land areas, particularly in regionsthat are not immediately adjacent the watercourses themselves. A properconcentration of diamonds is secured across the cutting faces of thebit, there being more diamonds around the cutting faces adjacent theoutside or reaming portions of the bit than on the inside, which, ofcourse, is desirable since the circumference traversed by the outerportions of the bit during each revolution is much greater than thecircumference covered by the inner portion of the bit, the outer portionbeing required to remove more formation than inner portion and beingsubjected to a greater total amount of work.

The inclination of the watercourse portions 210 along the reaming face16 of the bit also results in aproper cleaning and cooling of suchreaming face, since the fluid will not all remain in the inclinedwatercourses, but will tend to move in a direction generally parallel tothe axis of the bit, flowing from one waterway, across the inclinedreaming lands 22c, and into the next waterway. In so flowing across theland 220, it cleans and cools the latter.

The inventor claims:

1. In a rotary drill bit: a body having a drilling face adapted toengage the bottom of the hole in which the bit is operating and a fluidpassage extending longitudinally therethrough and opening into saiddrilling face, said drilling face containing a plurality ofsubstantially uniformly spaced generally'spiral watercourses to providesubstantially uniformly spaced generally spiral lands between saidwatercourses, each land being engageable with the bottom of the holeacrosssubstantially the full width of the land, cutting-elements securedto said lands for operation upon the'bottorn ofthe hole, each of 'saidspiral watercourses commencing at said fluid passage and extendinglaterally outwardly therefrom to the outer portion of said body atanincreasing angle to a radial line fromthe body. axis to-thecommencementof said watercourse, the arcuateextent of each watercourse and landaround the drilling face being substantially less than 360 degrees.

2. In a rotary; drill bit: abody havingaa drilling face adapted toengage 'thebottom ofthe hole in which'the bit is operating. and a fluidpassage extending longitudinally therethrough andopeningainto saiddrilling ;f'ace, said drilling face containing aplurality ofspaced-generally spiral watercourses to provide spaced generally spirallands betweensaid watercourses, each land being engageable with thebottom of the hole across substantially the full width of the land,cutting elements [secured -to said lands-for-operation upon the bottomof the hole, each of said spiral watercourses commencing at saidfluidpassage and extending-laterally outwardly therefrom to the outer portionof said body at an increasing angle to a radial line from the body axisto the commencement of said watercourse, the arcuate extent of eachwatercourse and land around the drilling face being substantially lessthan 360 degrees.

3. In a rotary drill bit: a body having a drilling face adapted toengage the bottom of the hole in which the bit is operating and a fluidpassage extending longitudinally therethrough and opening into saiddrilling face, said drilling face containing a plurality ofsubstantially uniformly spaced generally spiral watercourses to providesubstantially uniformly spaced generally spiral lands between saidwatercourses, each land being engageable with the bottom of the holeacross substantially the full width of the land, cutting elementssecured to said lands for operation upon the bottom of the hole, each ofsaid spiral watercourses commencing at said fluid passage and extendinglaterally outwardly therefrom to the outer portion of said body at anincreasing angle to a radial line from the body axis to the commencementof said watercourse, the arcuate extent of each watercourse and landaround the drilling face being substantially less than 360 degrees, eachwatercourse having a substantially 7 uinform width throughout itslength, each land having a substantially uniform width throughout itslength.

4. In a rotary drill bit: a body having a drilling face adapted toengage the bottom of the hole in which the bit is operating and a fluidpassage extending longitudinally therethrough and opening into saiddrilling face, said drilling face containing a plurality of spacedgenerally spiral watercourses to provide spaced generally spiral landsbetween said watercourses, each land being engageable with the bottom ofthe hole across substantially the full width of the land, cuttingelements se-' cured to said lands for operation upon the bottom of thehole, each of said spiral watercourses commencing at said fluid passageand extending laterally outwardly therefrom to the outer portion of saidbody at an increasing angle to a radial line from the body axis to thecommencement of said watercourse, the arcuate extent of each watercourseand land around the drilling face being substantially less than 360degrees, each watercourse having a substantially uniform widththroughout its length, each land having a substantially uniform widththroughout its length.

5. In a rotary drill bit: a body having a drilling face adapted toengage the bottom of a hole in which the bit is operating and a fluidpassage extending longitudinally therethrough and opening into saiddrilling face, said drilling face containing a plurality ofsubstantially uniformly spaced smoothly curved watercourses to providesubstantially uniformly spaced smoothly curved lands between saidwatercourses, each land being engageable with the bottom of the holeacross substantially the full width of the land, cutting elementssecured to said lands for operation upon the bottom of the hole, each ofsaid watercourses commencing at said fluid passage and extendinglaterally outwardly therefrom to the outer portion of said body at anincreasing angle to a radial line from the body axis to the commencementof said watercourse, the arcuate extent of each watercourse and landaround the drilling face being substantially less than 360 degrees.

6. In a rotary drill bit: a body having a drilling face adapted toengage the bottom of a hole in which the bit is operating and a fluidpassage extending longitudinally therethrough and opening into saiddrilling face, said drilling face containing a plurality ofsubstantially uniformly spaced smoothly curved watercourses to providesubstantially uniformly spaced smoothly curved lands between saidwatercourses, each land being engageable with the bottom of the holeacross substantially the full width of the land, cutting elementssecured to said lands for operation upon the bottom of the hole, each ofsaid watercourses commencing at said fluid passage and extendinglaterally outwardly therefrom to the outer portion of said body at anincreasing angle to a radial line from the body axis to the commencementof said watercourse, the arcuate extent of each watercourse and landaround the drilling face being substantially less than 360 degrees, eachwatercourse having a substantially uniform width throughout its length,each land having a substantially uniform width throughout its length.

7. In a rotary drill bit: a body having a convex drilling face adaptedto engage the bottom of a hole in which the bit is operating and fluidpassage means extending longitudinally through and opening into saiddrilling face, said drilling face containing a plurality ofsubstantially uniformly spaced generally spiral watercourses to providesubstantially uniformly spaced generally spiral lands between saidwatercourses, each land being engageable with the bottom of the holeacross substantially the full width of the land, cutting elementssecured to said lands for operation upon the bottom of the hole, each ofsaid spiral watercourses commencing at said fluid passage means andextending laterally outwardly therefrom to the outer portion of saidbody at an increasing angle to a radial line from the body axis to thecommencement of said watercourse, the arcuate extent of each watercourseand land around the drilling face being substantially less than 360degrees.

8. In a rotary drill bit: a body having a convex drilling face adaptedto engage the bottom of a hole in which the bit is operating and fluidpassage means extending longitudinally through an opening into saiddrilling face, said drilling face containing a plurality ofsubstantially uniformly spaced smoothly curved watercourses to providesubstantially uniformly spaced smoothly curved lands between saidwatercourses, each land being engageable with the bottom of the holeacross substantially the full width of the land, cutting elementssecured to said lands for operation upon the bottom of the hole, each ofsaid watercourses commencing at said fluid passage means and extendinglaterally outwardly therefrom to the outer portion of said body at anincreasing angle to a radial line from the body axis to the commencementof said watercourse, the arcuate extent of each watercourse and landaround the drilling face being substantially less than 360 degrees.

References Cited in the file of this patent UNITED STATES PATENTS817,296 Besson Apr. 10, 1906 2,381,415 Williams Aug. 7, 1945 2,612,348Catallo Sept. 30, 1952 FOREIGN PATENTS 979,107 France Apr. 23, 1951

